The study deals with the possibility of elimination of stagnation of thermal systems. The state of stagnation of thermal systems leads to overheating and evaporation of the heat transfer medium, which increases pressure and can lead to damage to the solar thermal system. Stagnation can occur due to a fault and stopping of the circulation pump, which causes the circulation of the heat transfer medium to stop. Another possibility is to achieve thermal saturation in the system, which can be affected by low heat consumption from the system. Elimination of stagnation is possible by various construction designs of collectors or by using other technical means. This study describes an experiment verifying the usability of a thermal collector’s tilting system to eliminate thermal stagnation of the system. The system is fully automatic, and when recording the limit values, ensures that the panel is rotated out of the ideal position, thus reducing the amount of received energy. In this way, the temperature of the medium in the system can be reduced by up to 10% in one hour. In the case of thermal saturation of the system, the solution is the automatic circulation of heat-transfer fluid through the system during the night and the release of thermal energy to the outside. These results suggest that the methods used actively eliminate stagnation of thermal systems.

Alkylate produced by catalyzed reaction of isobutane and olefin-rich streams is a desired component for gasoline blending. Fractionation of the alkylation reactor effluent is energy demanding due to the presence of close boiling point components and solutions cutting its energy intensity; expenses associated with this process are investigated intensely nowadays. This paper presents a novel conceptual design and techno-economic analysis of alkylation reaction effluent fractionation revamp to reach a cut in energy costs of the fractionation process without the need to revamp the rectification columns themselves, providing thus an alternative approach to a more sustainable alkylation process. Two cases are considered—A. additional steam turbine installation or B. combustion engine-driven heat pump-assisted rectification. Mathematical modeling of the considered system and its revamp is applied using the “frozen technology” approach. Real system operation features and seasonal variations are included considering the refinery’s combined heat and power (CHP) unit operation and CO₂ emissions balance both internal and external to the refinery. Case A yields an expectable yearly benefit (saved energy minus additionally consumed energy minus CO₂ emissions increase; expressed in financial terms) of €110–140 thousand, net present value (NPV) of −€18 to €272 thousand and produces 3.3 GWh/year of electric energy. Case B delivers a benefit of €900–1200 thousand, NPV of −€293 to €2823 thousand while producing 33 GWh/year of electricity. Both cases exhibit analogous simple payback periods (8–10 years). Marginal electric efficiency of Case B (78.3%) documents the energy integration level in this case, exploiting the system and CHP unit operation synergies. CHP unit summer operation mode and steam network restrictions significantly affect the seasonal benefit of Case B. CO₂ emissions increase in both cases, Case A and Case B, considering the refinery level. However, including external CO₂ emissions leads to emissions decrease in both cases of up to 26 kton/year (Case B.) The presented results document the viability of the proposed concepts comparable to the traditional (reference) solution of a high performance (COP = 8) heat pump while their performance sensitivity stresses the need for complex techno-economic assessment.

The aim of the article is to analyze the properties of artificial muscle system and effectiveness evaluation of the application of pulse width modulation in terms of improving the dynamic properties. In terms of dynamic properties, pneumatic artificial muscles represent a very complicated nonlinear structure. For this reason, the design of a robust positioning control system for pneumatic artificial muscle devices is demanding because, apart from the above-mentioned nonlinearity (because of air compressibility, air flow variability through valves, etc.), this is a time-and-parameter invariant system. The aim of the article is to evaluate the influence of pulse width modulation in pneumatic artificial muscle systems with regard to the accuracy and stability of the position achieved in the repeat mode, as well as the elimination of the adverse effect of the oscillation. The efficiency of the proposed control algorithm is demonstrated by experiments with external workload and no load.

Paper deals with the issue of low frequency magnetic fields from the frequency range up to 250Hz and range of the magnetic induction 2.10 ⁻⁹ to 2.10 ⁻⁵ T affecting the crew of the mobile devices measured under the influence of external and internal magnetic field sources. On the basis of the generated magnetic field scheme, measured magnetic induction values were evaluated. The measured sources of magnetic induction were the Suzuki SX4 and the Nisan Leaf and their comparisons.

The main idea of using combined heat and energy production is to reduce usage of primary fuels and with that connected reducing of pollutions due to the integration of renewable energy sources and with regard to the natural environment. Presented contribution is dedicated on issue on the operation of a cogeneration unit integrated in central heating system. The purpose of currently contribution is to analyse and compare effectivity of cogeneration unit in each summer and winter season.